COM specifications need to be clarified

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Greetings,

I need to know about some COM specifications and terminologies. I read a good article here about COM, Introduction to COM - What It Is and How to Use It, however, there are few things I still do not understand and I hope that someone could help me in that. Firstly the article states that

Quote:
multiple inheritance is not allowed with interfaces

On the other hand, the article mentioned a method on the IUnknown interface called

Quote:
QueryInterface()

which can be used to request a pointer from a COM object if the object's class implements more than one interface. So I am confused is inheriting from multiple interfaces (i.e., class : interface1, interface2, etc...) is allowed/not allowed?!!!. Also do we pass a pointer of interface type to the CoCreateInstance() method along with the class name as a form of polymorphism as there may be multiple classes each implement the same interface in its on way?. Those are the first two questions

What I have tried:

Read an article about COM on the forum to understand what are COM objects

Posted 9-Sep-17 19:29pm

Amr Mohammad Rashad

Updated 9-Sep-17 21:52pm

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CPallini · Accepted Answer · 2017-09-09T21:50:00

Solution 1

COM interface is not C++ interface (COM 'class' is not C++ 'class' as stated in the article). Have a look at COM Objects and Interfaces (COM)[^]. A COM class may expose multiple interfaces, but no interface multiple inheritance is implied in that.

Posted 9-Sep-17 21:50pm

CPallini